Field
Implementations of the present disclosure generally relate to forming protective layers on mechanical components, and more particularly, to electro-chemically forming coating such as yttria or yttrium oxide on semiconductor processing equipment.
Description of the Related Art
Conventionally, semiconductor processing equipment surfaces include certain coatings thereon to provide a degree of protection from the corrosive processing environment or to promote surface protection of the equipment. Several conventional methods utilized to coat the protective layer include physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma spraying, aerosol deposition, and the like. However, these conventional methods are unable to satisfactorily coat semiconductor equipment, especially in areas having small holes or plenums, such as showerheads.
FIGS. 3A and 3B respectively illustrate partial sectional views of a showerhead 320 and a faceplate 325 coated using conventional methods, such as thermal spraying or e-beam deposition. As shown in FIG. 3A, a showerhead 320 is formed from aluminum and includes a plurality of plenums 321 formed therein (two are shown). The plenums 321 may optionally include beveled edges 322 at one end thereof. Using conventional coating techniques, the beveled edges 322 are not coated with a protective coating 323 due to limitations of conventional coating techniques. For example, conventional techniques are unable to adequate coat substrates near plenums due to the directional deposition nature of conventional techniques. Conventional techniques thus leave the beveled edges 322 exposed, thereby contributing to contamination in the presence of plasma via reaction of the uncoated surfaces with the plasma. The unprotected surfaces which are exposed to plasma are easily degraded, thus introducing undesired particulate matter to the process region, and as a consequence, reducing device quality.
FIG. 3B illustrates a faceplate 325 including plenums 326 having a protective coating 327 deposited thereon. Similar to the showerhead 320 described above, conventional techniques are unable to adequately coat the faceplate 325, particularly the plenums 326. While upper surfaces of the faceplate 325, which are generally adjacent a deposition source during deposition of the protective coating 327, may be coated, the interior surfaces of the plenums 326 remain uncoated. The uncoated surfaces contribute to contamination within a process chamber due to undesired interaction with processing plasmas.
Therefore, there is a need for improved deposition methods for protective coatings.